613 Seminar: Tamas Varnai


Every hour or two, the Earth Polychromatic Imaging Camera (EPIC) onboard the DSCOVR spacecraft provides unique full-color images of the sunlit side of the Earth from the L1 Lagrangian point, which is about four times farther from Earth than the Moon is. Casual glances at such images often reveal bright colorful spots that stand out markedly from their surroundings. Such spots often appear over both ocean and land. Tracking the colorful spots using an automated image analysis algorithm reveals that they are caused by sun glint. The presentation will discuss the analysis of glints identified in a yearlong dataset of EPIC images, including the finding that a substantial fraction of all sun glints is caused by specular reflection from horizontally oriented ice crystals floating in clouds. The talk will also outline possibilities for using EPIC glint observations to characterize the prevalence, size, tilt, and radiative impacts of horizontally oriented ice crystals that float in clouds. 

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